Electrically controllable and/or electrically powered locks are known. Such locks must be set to operate as either fail safe or fail secure. A fail safe lock automatically reverts to an unlocked state when its power supply is interrupted, for example during a power failure. A fail secure lock automatically reverts to a locked state when its power supply is interrupted.
Australian patent No. 657349 discloses an example of a known type of electrically controllable and powered mortice lock which can be set as fail safe or fail secure by adjusting components through openings in the side panels of the lock or after disassembly of the lock. The disadvantage of this arrangement is that the lock must be removed from the door in order to change the lock from fail safe to fail secure.